Hitherto, the many fluid flow metering requirements have resulted in numerous different types of flow meters. The operational principles of flow meters vary a lot; listed here are a few classes: differential pressure flow meters, mass flow meters, area flow meters, electromagnetic flow meters, positive displacement flow meters, and open channel flow meters. All of these have specific areas of application but have also their limitations, as for example: some do not operate in reverse flow conditions; some must be mounted only in one position; some do not work well with soily or opaque liquids; some require individual calibration; some are not easily convertible to digital display output nor remote display; some must have see-through tubes; and some may become damaged by pressure variations or by changes in physical state of the fluid being measured.
One aspect appears to be common to a great many flow meters: the price--they are quite expensive. In many cases this is the result of the intricate nature of the device and the resultant high degree of accuracy required in manufacturing the component parts. In other cases individual calibration is a necessary requirement leading to the high price.
The idea in the present invention is to have as a moving part a ball and as a housing material having groves and holes, through which fluid may flow unobstructively, thus causing the ball to follow the total volumetric velocity of the fluid without leaving the housing body. This permits the revolutions to be counted, and from this volume, flow rate and other data can be computed, indicated, recorded and controlled.
It is an object of the present invention to accomplish accurate measurement of fluid flow in a way that allows inexpensive fabrication of the device through mass production.
Other objects of this invention are to make the device: respond well to changes in flow over a wide range of flow rates, especially in the laminar region; to handle pure fluids as well as true solutions, colloidial dispersions and suspensions of fluids; handle high viscosity liquid and non-Newtonian fluids; unsusciptible to changes in viscosity or temperature of the liquid; offer little resistance to fluid flow; unaffected from hammer effect; and capable of measuring pulsating flow.
Further objects of this invention are to provide a device which is simple in design, construction and operation; offers ease of installation and maintenance; and has long service life.
In this invention the ball in the housing will follow the fluid flow at a velocity very close to the velocity of the fluid. This invention may be classed as a positive displacement flow meter and an area-velocity integrating type flow meter as it has the characteristics of both. Making reference here to other similar looking devices having a spinning ball and two orifices on the outer surface of the toroid, and used as flow indicators, the basic difference to these is in the arrangement of the orifices, explained later, which makes these flow indicator devices perform differently and not part of the positive displacement flow meter category.
For the fluid there are one inlet and one outlet orifice located so that when the fluid entering at the inlet orifice has made almost one full round within its circular passageway, it will exit at the outlet orifice located almost opposite the inlet orifice. The ball will otherwise follow the mass of the fluid but, due to the shape and size of the outlet orifice, will not exit but travels past the boundary line between the incoming and outgoing fluids, only to start another cycle in the device. The pushing force of the fluid is continuous, without interruptions, between the inlet and outlet orifices.
The toroidal passageway in the housing is as round and circular in shape with as smooth a surface as can be manufactured without extra effort. The ball is only slightly smaller than its passageway to allow free travel, touching the wall of the passageway only at one point, as a rule, or occasionally, at two points on locations where an orifice is located, or at no point at all.
The inlet and outlet orifices in the passageway carry through the housing to the outside surface where connections to pipe, hose, tube or other fluid carrying enclosure or fitting can be made. A good direction to the holes thus formed is close to the line which is 17 degrees away from the direction of the tangent to the center line of the toroidal passageway, the 17 degree-line being on the perpendicular plane to the plane defined by the toroid's centre line and the tangent to the centre line. The above direction minimizes friction and turbulence; however, deviations from said direction up to 45 degrees to the plane defined by the centre line do not make the device inoperative. The two orifices, formed where the holes from the exterior connection means meet the toroidal passageway, are on the opposite sides on the passageway but slightly off, allowing the fluid to flow easily into and out of the passageway.
The most prevelent application of this invention is envisioned as that of measuring flow rates of liquids in situations where digital read-out is required, or, where signals, directly proportional in frequency to the flow rate, carry the information to the processor. To the large family of different types of flow meters this invention is a newcomer, suitable for many uses. For example, this invention can be used when an inexpensive device with electronic pulse output, together with a signal processor, is required, e.g. in aircraft for measurement of gasoline consumption. In automobiles and boats and ships this invention can provide similar invention.
In any watercraft this invention, when installed to read water speed, can measure the speed of the vessel, the distance travelled, etc.
In industrial applications the flow rate of many types of liquids can be measured because the invention can be made of metals or plastics. Monitoring, batching and totalizing of volumes of liquids as part of process control is just a matter of selecting the appropriate signal processor.
From the foregoing it should be apparent that the application of the present invention overcomes numerous objections heretofore encumbering the measuring of fluid flow, one important feature being the freedom of mounting in any position.